Making a Mobile "Roadblock"
to keep the Tie moving in front of the player you can add some random motion on the Y axis with a constraint to keep it in the view, and to keep the Tie moving in front of the object on the X-axis you add some motion on the x axis:



to make a bullet be fired at a position without traking an object you can add another object that will track the hitBox and fire the bullets, when the box move the bullets will not track it